This invention relates to an apparatus for, and a method of, treating occluded vessels (e.g. an artery) and capturing friable emboli which may break away from the lesion in the vessel during the interventional procedure. The apparatus and method of the present invention are especially useful when performing carotid interventional procedures in order to prevent emboli or debris from entering and occluding downstream blood vessels leading to the brain which, if blocked, may cause a stroke. However, the system and method of this invention can be adapted by a person of ordinary skill in the art for use in numerous other vascular interventional procedures.
In recent years, numerous procedures have been adapted for expanding blood vessels (e.g. arteries), at the positions of lesions in the blood vessels, so that blood can flow through the blood vessels without obstruction from the lesions. In the process of expanding such blood vessels at the positions of the lesions, emboli may become detached from the lesions and enter the bloodstream and subsequently migrate through the patient""s vasculature to occlude small diameter vessels which supply oxygenated blood to sensitive organs such as the brain, where such blockage may induce trauma.
Procedures have also been adapted in recent years for preventing embolic debris from flowing through the vessels in the direction of the blood flow. For example, filters have been provided for trapping the emboli. When lesions develop in the carotid artery of a patient, the placement of a filter in the patient""s vasculature can somewhat reduce the movement of the emboli to the blood vessels supplying the patient""s brain, thereby preventing strokes from occurring.
Such filters are usually delivered in a collapsed position through the patient""s vasculature and are then expanded once in place in the patient""s blood vessel to trap the emboli. After emboli have been trapped, the filter is collapsed to remove the filter (with the trapped emboli) from the vessel. However, it is possible for some of the trapped emboli to escape from the filter during the time that the filter is being collapsed and/or removed from the blood vessel after being collapsed. When an interventional procedure is being performed in a carotid artery, even a trace release of emboli can be devastating. For this reason, attempts to treat lesions in the carotid arteries have been somewhat limited due to the danger presented if all of the embolic debris is not collected during the procedure.
Therefore, in light of the above, it would be desirable for an apparatus and method which can be utilized to treat an occluded vessel and trap any emboli that may be formed during the vascular procedure. Such an apparatus and method must also prevent the emboli from escaping from the filter during the time that the filter is being collapsed and/or removed from the blood vessel (e.g. the carotid arteries). Such a device or method should be easy and safe to deploy, and be easily removed from the vasculature with minimal adverse impact or immulogical response to the patient.
The present invention addresses the above-mentioned needs by providing a catheter apparatus which can be used to treat an occluded vessel and trap any embolic debris which may be released into the bloodstream during the procedure. The catheter apparatus includes both a lesion dilating member (the interventional device) and an emboli capturing filter assembly which can be simultaneously introduced into the patient""s vasculature. In one preferred embodiment, the lesion dilating member is an expandable member, such as a dilatation balloon, which is disposable at the lesion position in the vessel (e.g. a patient""s artery) and dilatable to open the vessel. The emboli capturing filter assembly can be formed from a perfusion member (a balloon) which has a number of channels formed at its outer surface and filter material placed over the outer surface of the balloon. The emboli-capturing assembly is distal to, and placed downstream from, the lesion dilating member to capture, when the perfusion member is expanded, any emboli released into the bloodstream of the vessel. The emboli will be retained within a reservoir formed on the emboli capturing assembly until the procedure is completed. Thereafter, the perfusion member (with the trapped embolic debris) can be deflated and removed from the vasculature.
The perfusion member may be any one of a number of conventional perfusion balloons known in the art. Perfusion balloons are sometimes utilized during angioplasty and other interventional procedures when blood perfusion past an inflated dilatation balloon is required. A conventional perfusion balloon usually has a number of channels formed along the balloon""s outer surface to create conduits to allow blood to pass through when the perfusion balloon is inflated within a blood vessel. The perfusion balloon may have any one of a number of different cross-sectional shapes, such as a star-shape, and the channels may be straight or spiral. The shape of the balloon and the number of channels formed on the perfusion balloon should ensure that adequate blood flow past the inflated balloon is achieved and maintained throughout the procedure.
A filtering material is placed over the outer surface of the perfusion member to create a xe2x80x9cpocketxe2x80x9d with each channel of the perfusion member and traps any embolic debris that may pass through the inlet of the channel. This filtering coverage starts distally from the proximal end of the perfusion member and terminates at the distal end of the perfusion member to create a deep xe2x80x9cpocketxe2x80x9d or xe2x80x9creservoirxe2x80x9d which allows for the free flow of blood but catches any emboli which may be released in the bloodstream. After the perfusion member is completely expanded against the vessel wall, blood and embolic debris enters the xe2x80x9cpocketxe2x80x9d formed between the filter and the perfusion member.
The perfusion member may illustratively have peaks and channels formed between adjacent peaks. The depth of the channels at the center region of the perfusion member is usually less than at the distal end of the perfusion member. In one preferred embodiment, the perfusion member has a star-shaped cross-section which creates individual channels that cooperate with the filtering material to create the filtering xe2x80x9cpocketsxe2x80x9d which receive the blood and any embolic debris released into the bloodstream. The size and depth of the channel at the center region are designed to be shallower than the channel as it proceeds distally along the perfusion member. The smaller opening of the channel where the coverage of the filter begins permits sufficient fluid flow into the channel with the larger or deeper portion of the channel at the distal end of the perfusion balloon forming the reservoir for capturing and retaining the embolic debris. When deflated, the perfusion member provides for retention of the trapped emboli in the perfusion member. Due to the unique construction of the shallower channel at the inlet opening of the perfusion member, any trapped emboli in the distal reservoir portion is less likely to be discharged out of the smaller channel opening once the perfusion member is deflated. The filtering material may be made from any flexible and porous material with dimensions to allow fluid (blood) to pass through and block the embolic debris.
In use, the catheter apparatus is initially disposed in a vessel with the lesion dilating member juxtaposed to the lesion and the emboli-capturing assembly positioned downstream from the lesion in the fluid flow direction. The perfusion member is initially inflated to deploy the filtering portion of the catheter and the lesion dilating member is then dilated to expand the vessel at the lesion position. The lesion dilating member is thereafter deflated to ensure that any emboli from the lesion which may be trapped against the inflated dilating member is allowed to travel with the blood flow into the trapping xe2x80x9cpocketxe2x80x9d of the perfusion member. The perfusion member is thereafter deflated and removed (with the trapped emboli) from the patient""s vasculature.
Other features and advantages of the present invention will become more apparent from the following detained description of the invention, when taken in conjunction with the accompanying exemplary drawings.